A video recording can be communicated and/or stored in digital form as encoded image data defining a sequence of displayable pictures for video playback. Some video encoding formats are defined by standards organizations to facilitate broad acceptance by industry and consumers (e.g., H.261, MPEG-1, H.262/MPEG-2, H.263, MPEG-4 Part 2, H.264/AVC, SMPTE VC-1, and H.265/HEVC). Video encoding typically includes a compression aspect that reduces the transmission and storage requirements associated with the video recording. For example, compressed video occupies less storage on a computing device and can be transferred (e.g., streamed) in a shorter period of time to/from the computing device. When the digital data is decoded, the data for each encoded picture in the coded video sequence is decoded to generate a displayable picture for presentation on a display, such as a computer screen, phone screen, or other display device.
In addition, a graphics processor is often used in combination with a host processor in a computing system to off-load certain processor-intensive decoding operations. The interaction between a host-processor-executed decoder and a graphics processor in decoding encoded image data can dramatically improve system performance. Such interaction can be dependent upon the standard used to encode the video and can itself be governed by a standardized interface.
Because normal playback is the most frequently used mode of operation in a video playback system, video encoding standards are often focused on a normal playback of video. As a result, other playback modes, which may be referred to as “trick play” operation (e.g., fast forward, reverse, skip ahead/forward seek, skip back/rewind, etc.) can present decoding challenges. For example, decoding for such a trick play operation may rely on video data that is not yet completely transferred, decoded, or otherwise available when that trick play mode is executed. Accordingly, the unavailable video data can lead to poor performance and/or poor picture quality during trick play operation.